Flying against the wind a jet travels 7740 miles in 9 hours. flying with the wind the same jet travels 4000 80 miles in 3 hours. what is the rate of the jet in still air and what is the rate of the wind?

Scores on a university exam are normally distributed with a mean of 78 and a standard deviation of 8. the professor teaching the class declares that a score of 70 or higher is required for a grade of at least “c.” using the 68-95-99.7 rule, what percentage of students failed to earn a grade of at least “c”?